1. Field of the Invention
The apparatus and method of the present invention is for transversely cutting into segments a continuous strip-like web of material moving along the strip axis.
2. Description of the Prior Art
Probably the most commonly used types of apparatus for transversely cutting a moving strip-like web are the guillotine-type cutters. These apparatus are characterized by a blade which completely spans the web in the transverse direction and which reciprocates in a plane perpendicular to the longitudinal axis of the web. The period of reciprocation together with the speed of the web along the longitudinal axis determine the lengths of the cut material. While this general type of cutting apparatus has been used satisfactorily in the insulation-board fabrication industry, the apparatus is satisfactory only for certain limited applications, namely those involving low web speeds and homogenous insulation materials.
Modern insulation-board materials and forming techniques have rendered the guillotine-type cutting apparatus unsatisfactory for several reasons. Modern techniques and equipment have enabled the rate at which the continuous web of material is formed to be increased dramatically, and production and conveying speeds of 200 feet per minute are now possible with some insulation materials. At these high production speeds, the short but finite length of time that the blades of the guillotine-type cutters engage the web result in a "pile up" of the material behind the blade. This pile up can cause unacceptable deformation of the board edge, resulting in scrap material, and can also result in jamming of the forming and conveying machines at high production speed. Hence, production speeds for guillotine-type cutting apparatus are understandably limited to well under 200 feet per minute in the insulation-board industry.
Another and equally significant limitation on the guillotine-type cutting apparatus is that it is difficult to completely cut composite or laminated insulation material without deforming the structure of the material immediately adjacent to the cut. The variations in the longitudinal tensile strengths of the separate materials in the composite or lamination, together with the generally low compressive strength of some foamed insulation materials, are responsible for this limitation. For some of the newer composite insulation materials such as fiberglass-reinforced foamed polyurethane insulation board, this limitation renders the guillotine-type cutter almost totally unacceptable.
Some attempts have been made in the insulation-board industry to circumvent the problem of cutting moving webs of composite materials, but these have achieved only marginal success. One such attempt involves apparatus which accomplishes the cutting with a travelling saw element. Certain problems and limitations remain even with the use of such apparatus for cutting composite insulation materials. It is understood in the insulation-board industry that saw elements can have unacceptably high waste rates. For certain types of insulation, a large percentage of the saw-cuttings is in the form of dust. This dust can be hard to control and under certain conditions can constitute a fire hazard or a health hazard. For instance, dust from saw-cut insulation board containing asbestos, a common insulation material, would be expected to be particularly dangerous. And finally, certain materials, such as bituminous felt, which are often used in composite insulation materials adhere to and clog saw elements necessitating frequent shutdowns for cleaning and a consequent increase in downtime costs.